1. Field of the Invention
The present invention relates to a chemical composition and its use for remediation of waste streams including those from municipal and industrial sources containing high levels of contaminants such as fat, oil, grease, soluble and insoluble heavy metals, organic matter and inorganic matter. The composition includes natural minerals such as clay, zeolites, apatite, Dolomitic lime, fly ash, cement, coagulants, and flocculants which are either cationic, anionic or nonionic in nature.
2. Description of Prior Developments
Waste streams generally contain contaminants such as fat, oil, grease, heavy metals, organic substances such as phenolics, chlorinated compounds, and inorganics such as fluoride, sulfate, phosphate, cyanide, chromates, arsenic and selenium, at levels considered hazardous to the environment and which could pose a risk to public health. Such contaminants must be removed or their levels reduced to meet government discharge standards prior to discharging the waste into the environment.
Waste streams are generally treated by chemical, physical or mechanical means, or by combinations thereof. Techniques used in conventional wastewater treatment for removing emulsified soluble or floating oils, suspended solids, heavy metals, organic and inorganic matters basically involve several steps such as demulsification, oil skimming, metal precipitation, flocculation, and settling. Each step takes place in a separate tank and the entire treatment requires multiple adjustments of pH and the addition of acid, emulsion breakers (demulsifiers), lime/caustic, coagulants, and polymer solutions.
This conventional multi-step process is time consuming and has a high demand for equipment, i.e., it requires a number of treatment tanks equipped with agitators, pumps, liquid chemical dispensers and feed lines, chemicals, manpower, and energy. In each step, wastewater may be recirculated several times for retreatment to effect the maximum removal of contaminants, before it goes to the next step.
Moreover, the generated solid waste typically contains high levels of heavy metals and other hazardous substances which are usually leachable. The waste therefore requires further treatment to render the solid waste non-hazardous before it can be safely disposed. The cost of the disposal of hazardous waste is three to four times the disposal cost of nonhazardous waste.
The use of chemical agents for treating wastewater is disclosed in U.S. Pat. Nos. 3,956,117, 3,428,558, 3,968,036, 4,167,481, 4,517,094, 5,336,704, and 5,415,808. These earlier inventions, however, suffer from disadvantages relating to their limited applications, i.e., the chemical agents are not stand-alone products. For example, U.S. Pat. No. 3,956,117 discloses the use of cationic polymers for removal of oil; U.S. Pat. Nos. 3,428,558, and 5,415,808 disclose polymeric flocculants and their use in the removal of suspended particles; U.S. Pat. Nos. 4,167,481 and 5,336,704 disclose chemical compositions for removal of metals; and U.S. Pat. Nos. 3,968,036 and 4,517,094 disclose methods for removal of organics.
None of these earlier inventions discloses a single agent or composition that is capable of simultaneous removal of contaminants such as oil and grease, suspended solids, heavy metals, and other organic and inorganic matter. Moreover, in most cases, prior treatment processes are also tedious and laborious such as those disclosed in U.S. Pat. Nos. 4,167,481 and 4,517,094 or those inventions wherein a conventional multi-step process is required when polymeric flocculants are used. Most importantly, these earlier inventions are not cost effective and generate solid wastes that are normally hazardous and must be further treated prior to disposal.
More recently, attention has been focused on the development of a single product system for treatment of waste streams, such as disclosed in U.S. Pat. Nos. 3,953,330, 4,332,693, 4,415,467, and 4,765,908. These products suffer from disadvantages due to non-versatility, i.e., they are generally applicable to a specific type of waste stream, e.g., oil, metals, or organic contaminated waste streams. Moreover, their manufacturing processes are complex, the compositions work in a narrow range of pH, they are slow to react with contaminants, and they produce solid waste that may not pass the Toxicity Characteristic Leaching Procedure test (TCLP) instituted by the US EPA. These products also do not work well in the presence of chelating and complexing agents, they usually require a pretreatment step to break the chelate or a post treatment step with a polishing agent, and they are costly to use on a commercial scale.
Accordingly, what is needed is an economical single treatment agent or chemical composition for remediation of waste streams, and more particularly industrial waste streams, which is capable of simultaneously and efficiently removing up to several thousand ppm of fat, oil, grease, suspended solids, soluble and insoluble heavy metals, and other organic and inorganic matters, resulting in treated water that meets discharge standards set by environmental authorities.
A further need exists for such a single treatment agent which leads to the formation of a fast settling floc that is easily dewatered.
A further need exists for a process that removes hazardous contaminants from a waste stream and isolates them in a stabilized non-leaching matrix.
A further need exists for such an agent and process which generates solid waste that does not require further treatment in order to pass the TCLP test and does not pose a hazard to the environment once disposed in a landfill.
A further need exists for such a composition that is very versatile and works effectively over a wide pH range of, e.g. 2-12, and has an uptake capacity that is independent of the presence of surfactants, detergents, hardness, and chelating/complexing agents.
A further need exists for such a composition which produces a non-slimy sludge which does not block or clog sludge filters such as filter presses.